Service difficulty report · Contactor · Cessna 172N

Difficulty date
November 9, 2000
Submitted
December 7, 2000
Operation
General aviation
Make and model
Cessna 172N
Aircraft time
8,292 hours
Engine
Lyc O320H2AD
Propeller
Mcauly 1C160DTM
Part
Contactor
Part number
ES10382585
Condition
Worn
Location
Rub Block
Part time
100 hours
Component
Magneto · Bendix · D4RN3000
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
O

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

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